The present invention relates to centerless grinding machines and in particular to conversion of a centerless grinding machine to use a servo motor to drive the regulating wheel.
Centerless grinding machines have long been utilized for providing very precise cylindrical parts and very smooth finishes. The machines provide a workpiece rest for supporting a workpiece between a grinding wheel and a regulating wheel. Conventional centerless grinding machines include a large constant speed electric motor connected to the regulating wheel through a series of gears, chains, and idlers. The gears allow the speed of the regulating wheel to be selected for grinding various materials and workpiece sizes. Unfortunately, the gears, chains, and idlers of convention centerless grinding machines are expensive to maintain and introduce mechanical vibrations into the regulating wheel which reduce the precision of the machine.
A known conversion for a centerless grinding machine directly connected a servo motor to a replacement regulating wheel spindle. As a result, the electric servo motor is exposed to the metal grindings necessarily resulting from the operation of the centerless grinder. Such exposure to very fine metal grindings creates a need for frequent maintenance and also results in shortened motor life. Further, the regulating wheel spindle is a very expensive element of a centerless grinding machine and such replacement is very high cost.
U.S. Pat. No. 5,569,059 for “System For Driving a Centerless Grinder Regulating Wheel” discloses a centerless grinding machine conversion including a speed controlled electric servo motor 106 mounted beside a top slide 100 and connected to the regulating wheel through a cylindrical cam unit 110 mounted inside the top slide. Further, U.S. Pat. No. 5,643,045 for “Retrofit Kit For Driving the Regulating Wheel of a Centerless Grinder,” discloses a conversion to an electric motor 26. The motor is mounted externally to the top slide 32 and drives the regulating wheel through a speed reducer and a toothed belt. The electric motor is mounted using an adapter plate which may be rotated to adjust belt tension. While both the '059 and the '045 patents replace the gears, chains, and idlers with an electric servo motor, the electric servo motor is again exposed to the metal grindings resulting from the operation of the centerless grinder and results in a need for frequent maintenance and short motor life. The '059 and the '045 patents are herein incorporated in their entirety by reference.